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Half of HIV+ Middle-Aged Meet Social Security Disability Threshold in Walk Test
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2nd International Workshop on HIV and Aging, October 27-28, 2011, Baltimore, Maryland
Mark Mascolini
Seven percent of 359 middle-aged HIV-positive people tested at the University of Colorado had poor performance on two functional status tools, and one third to one half had only moderate function [1]. Half failed to maintain a walking speed above 3.4 miles per hour and thus met a Social Security Administration criterion for disability. People with low versus high functioning on the three scoring systems had a higher risk of death according to the Veterans Aging Cohort Study (VACS) mortality risk index.
Diverse functional status instruments have been developed to study aging, but they have not been applied to middle-aged populations with HIV. University of Colorado investigators compared three functional status systems with each other and with the VACS mortality risk index in 45- to 65-year-old HIV-positive people with one or more viral loads below 48 copies while on a stable antiretroviral combination for more than 6 months. After reaching an undetectable load, no one had a blip or rebound above 200 copies. The researchers classified people as having high, moderate, or low function by Fried's Frailty Phenotype (FFP), the Short Physical Performance Battery (SPPB), and the 400-meter walk.
Study participants averaged 52 years in age (standard error [SE] 0.3), 85% were men, 65% gay men, 74% Caucasian, and 18% Hispanic. CD4 counts averaged 594 (SE 16), and 95% had a viral load below 48 copies. Fewer than 1% of the study group injected drugs or used cocaine, and only 4% downed more than 7 alcoholic drinks a week. One third smoked and one third had quit smoking.
About 7% of study participants had low function in the FFP and SPPB systems, and half had only moderate function by FFP or the 400-meter walk:
FFP:
Low function: 27 (7.5%)
Moderate function: 165 (46%)
High function: 167 (46.5%)
SPPB:
Low function: 26 (7%)
Moderate function: 110 (31%)
High function: 223 (62%)
400-meter walk:
Low function: 11 (3%)
Moderate function: 182 (51%)
High function: 166 (46%)
The three functional status instruments had fair agreement (61% to 64%, weighted Kappa 0.34 to 0.41).
Across all three function systems, more reported comorbidities and medications, diabetes, and psychiatric conditions independently predicted lower function, as did lower self-reported activity. Variables that significantly predicted lower function (P < 0.01) with the three individual instruments had moderate overlap between systems, with pain the only significant factor for all three systems:
FFP:
Pain
Falls
Neurologic disease
Psychiatric disease
SPPB:
Pain
Falls
Neurologic disease
Diabetes
Arthritis
Joint replacement
Hospitalizations
400-meter walk:
Pain
Obesity
Diabetes
Arthritis
Lung disease
The VACS mortality index, which ranges from 0 (lowest risk) to 165 (highest risk) [2], accurately predicted 5-year all-cause mortality in this group. Median VACS score was 18, and people with a score of 34 or higher had the highest death risk. In all three instruments evaluated, greater impairment corresponded with a higher VACS score. Score differences between low and high function were 8.6 for FFP (P = 0.03), 12.4 for SPPB (P = 0.001), and 11.9 for the 400-meter walk (P = 0.08).
Factors that raise the VACS score are older age, lower CD4 count, higher viral load, lower hemoglobin, higher FIB-4 fibrosis, lower estimated glomerular filtration rate, and hepatitis C coinfection [2] (see www.vacohort.org/74621_VACS_Index_Handout_19Nov10.pdf).
The researchers cautioned that their analysis is limited by its cross-sectional nature, by the dominance of white men in the population, and by inclusion criteria that probably favored people more engaged in medical care.
The University of Colorado team proposed that "measurement of functional status, identification of risk factors that may lead to functional compromise, and interventions to reduce risks could improve successful aging and maintenance of independence as persons with HIV age."
References
1. Erlandson KM, Allshouse AA, Jankowski C, et al. Prospective comparison of three functional assessments with the Veteran's Aging Cohort Study index in virologically suppressed HIV-infected adults. 2nd International Workshop on HIV and Aging, October 27-28, 2011. Baltimore, Maryland. Abstract O_08.
2. Justice AC, McGinnis KA, Skanderson M, et al; VACS Project Team. Towards a combined prognostic index for survival in HIV infection: the role of 'non-HIV' biomarkers. HIV Med. 2010;11:143-51. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3077949/?tool=pubmed
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